Resolving SMTP Server Secure Connection and Authentication Error in ASP.NET

Introduction:

In a previous article, I tried my best to explain how to send email or multiple emails using a Gmail account in asp.net using C# programming.

In this article, I focused on an issue which commonly occurs in this requirement to the developers i.e., resolving the SMTP Server Secure Connection and Authentication Error (5.5.1 Authentication Required) you can see the complete error message in the below image.

Let me show you how to resolve this problem.

Error Overview:

Possible Causes:

1. SMTP Authentication Configuration:

   Ensure that SMTP authentication is correctly set in your code. This is a crucial step in establishing a secure connection with the SMTP server.

2. Gmail Account Security Settings:

   If there are no issues with your SMTP connection in the code, the error might be due to Gmail blocking authentication from your server. This often occurs when logging in from a new location or device.

Solution:

Follow these steps to resolve the SMTP Server Secure Connection and Authentication Error:

1. Check SMTP Authentication:

   • Confirm that SMTP authentication is correctly implemented in your code. This ensures that your ASP.NET application can securely connect to the SMTP server.

2. Approve Less Secure Apps Access:

   • If Gmail has blocked authentication, visit the Gmail Security Center and log in to your Gmail account.
   • Google Security Center for Email
   • Click on "Access for Less Secure Apps" and turn on this option.

This step allows your ASP.NET application to access your Gmail account securely.

Conclusion:

By confirming proper SMTP authentication in your code and approving less secure app access in your Gmail account settings, you can overcome the SMTP Server Secure Connection and Authentication Error in ASP.NET. Following these steps ensures the secure and uninterrupted flow of emails from your ASP.NET application.